Artificial skin in perspective: concepts and applications

Abstract

SummarySkin, the largest organ of the human body, is organized into an elaborate layered structure consisting mainly of the outermost epidermis and the underlying dermis. A subcutaneous adipose-storing hypodermis layer and various appendages such as hair follicles, sweat glands, sebaceous glands, nerves, lymphatics, and blood vessels are also present in the skin. These multiple components of the skin ensure survival by carrying out critical functions such as protection, thermoregulation, excretion, absorption, metabolic functions, sensation, evaporation management, and aesthetics. The study of how these biological functions are performed is critical to our understanding of basic skin biology such as regulation of pigmentation and wound repair.Impairment of any of these functions may lead to pathogenic alterations, including skin cancers. Therefore, the development of genetically controlled and well characterized skin models can have important implications, not only for scientists and physicians, but also for manufacturers, consumers, governing regulatory boards and animal welfare organizations. As cells making up human skin tissue grow within an organized threedimensional (3D) matrix surrounded by neighboring cells, standard monolayer (2D) cell cultures do not recapitulate the physiological architecture of the skin. Several types of human skin recombinants, also called artificial skin, that provide this critical 3D structure have now been reconstructed in vitro. This review contemplates the use of these organotypic skin models in different applications, including substitutes to animal testing.

In vitro skin three-dimensional models and their applications

“…collagen, fibrin, gelatin) [37,45,48]. Since the cells can be recovered from the gels by proteases hydrogel systems are also convenient for molecular analysis (Western Blot, Polymerase Chain Reaction (PCR)) [40,43] and their transparency allows microscopy [38]. The costs are moderate.…”

“…To generate a cancer model, melanocytes and/or melanoma cells can be added [43]. Since skin cancer, psoriasis, and other skin diseases involve the complex cross-talk between various cell types and cytokines, 3D skin models that also contain immune cells are of great value.…”

Desenvolvimento de epiderme equivalente sobre membrana do tipo transwell e membrana biopolimérica

“…As culturas em monocamada são baseadas em um único tipo celular ou mais (cocultura) e para tanto utilizam células primárias ou linhagens celulares pré-estabelecidas (Corsini et al, 2009;Santos et al, 2009;Brohem et al, 2011 (Bell et al, 1983;(Brohem et al, 2011). Esses modelos são menos utilizados para a avaliação do risco do que os equivalentes de epiderme apesar de estarem disponíveis no mercado (TestSkin ® , Apligraf ® , AST-2000 ® , Skin2 ® ).…”

“…Além disso, nenhum desses equivalentes de pele foi validado pelo ECVAM (Centro Europeu para a Validação de Métodos Alternativos) e discute-se o fato de que a presença da derme não acrescentaria nenhum tipo de benefício à avaliação do risco. Este fato ainda é questionável, pois, a presença tanto da epiderme quanto da derme tornaria o modelo fisiologicamente mais relevante uma vez que permitem a investigação de interação célula-célula e célula-matriz extracelular recriando o microambiente tecidual (Spiekstra et al, 2005;Brohem et al, 2011). Essas interações podem modificar sensivelmente a ação toxica ou farmacológica das substâncias químicas.…”

“…Por fim, uma terceira tripsinização é feita, com tripsina 0,1% por 3 a 4 minutos a 37ºC, para coletar todos os queratinócitos que ainda permaneceram aderidos. Essa cultura pura de queratinócitos é mantidas em meio KGM Gold BulleKit (KBM-Gold Keratinocyte Basal Medium -Gold without Ca) suplementado com (KGM -Gold SingleQuot Kit) (Brohem et al, 2011) e isoproterenol (10 -6 M) em incubadora à 7,5% de CO2.…”